Obvious spoilery post (as one would assume at this point)
IDK if I agree that it would have been better being a 'bad end'. Those tend to come off as extreme, either nihilistic or preachy, in stories like this. I'd argue its satisfactorily bittersweet though. Its an ending that caters towards those that care about the characters and plot than morality or message.
Really, its a very conclusive ending overall. Though really it still sort of leaves you wondering what happens to those surviving. Jesse in particular is a broken person at this point and is far from done with the ordeal. I'd like to know what he decides to do after driving away in the El Camino. He's broke, the police are likely looking for him, he has no real family to support him, and his 'girlfriend' is dead and he has no way to care for the kid and arguably shouldn't try (though IDK if he would want to at this point since the kid would just remind him of his loss). If he were to hang out with his friends he'd likely end up using again (hell, that's fairly likely regardless).
He'll either start a new life as a miserable lonely fugitive like Walt was, turn himself in and go to prison (variable on how long), kill himself eventually (suicide), or kill himself (with drugs).
Like, I can't foresee a happy ending for him. Leaving his fate ambiguous is torture-some. The neo-nazi's killing his girlfriend was the last straw really at any chance of him living a semi-decent life in my view.